Custom configCustom element doesn't exist: picture-entity

It’s not a custom card, so you have to use the hui card trick:

type: 'custom:config-template-card'
variables:
  - 'states[''sensor.trash_first_next_item''].state'
entities:
  - sensor.trash_first_next_item
  - sensor.trash_first_next_date
card:
  type: 'custom:hui-picture-entity'
  entities:
    - entity: sensor.trash_first_next_item
      name: '${states[''sensor.trash_first_next_date''].state}'
      state_image:
        Geen: /local/afvalwijzer/geen.png
        gft: /local/afvalwijzer/gft.png
        papier: /local/afvalwijzer/papier.png
        plastic: /local/afvalwijzer/plastic.png
        restafval: /local/afvalwijzer/grijs.png

However, since v0.107 this also requires you to preload the card: